The present invention relates to a bump-bonding heating apparatus for heating a semiconductor wafer placed on the heating apparatus to a bump bonding temperature in a process of forming bumps at electrode portions on circuits formed on the semiconductor wafer, a bump bonding method to be carried out by using the bump-bonding heating apparatus, a bump forming apparatus equipped with the bump-bonding heating apparatus, and a semiconductor wafer having bumps bonded by the bump forming apparatus.
Conventionally, a bump forming apparatus is equipped with the bump-bonding heating apparatus. As shown in FIGS. 24 and 25, in the conventional bump-bonding heating apparatus 1, gas is jetted out, through gas jet paths 4 opened at a heat stage 2, to a semiconductor wafer 3 which has been carried into the bump-bonding heating apparatus and placed on the heat stage 2 so that the semiconductor wafer 3 is heated to a bump bonding temperature. By this gas jet, the semiconductor wafer 3 is rotated circumferentially of the semiconductor wafer 3 on the heat stage 2 so as to be set to a preset rotational angle. For such a gas-floating type direct turning method for the semiconductor wafer 3, only a gas supply unit 5 needs to be provided as a structure for turning the semiconductor wafer 3. This allows the bump-bonding heating apparatus 1 to be made compact, and thus this direct turning method is preferable.
However, the bump-bonding heating apparatus of the above structure has the following problems. That is, in the case where the semiconductor wafer 3 is a charge-producing semiconductor substrate that produces charges from temperature differences due to the heating to the bump bonding temperature or other reasons, the charge-producing semiconductor substrate, when mounted on the heat stage 2, is electrostatically adhered onto the heat stage 2 by the electrification of the charge-producing semiconductor substrate. Also, in order to turn the semiconductor wafer 3 to the preset rotational angle, it would be necessary to control a pressure, flow rate and the like of the gas jet according to a size and weight of the semiconductor wafer 3, making the apparatus difficult to handle. It is also difficult to turn the semiconductor wafer 3 to the preset rotational angle at high accuracy.
Meanwhile, without adopting the gas-floating type turning method for the semiconductor wafer 3, a structure in which the heat stage 2 with the semiconductor wafer 3 held thereto is rotated could be conceived. This structure, however, would involve increasing the size of the apparatus, disadvantageously.
The present invention having been accomplished with a view to solving these and other problems, an object of the invention is to provide a heating apparatus for bump bonding which does not involve large-sized apparatus configuration and which is easy to handle, a bump bonding method to be executed in the heating apparatus for bump bonding, a bump forming apparatus equipped with the heating apparatus for bump bonding, and a semiconductor wafer having bumps bonded by the bump forming apparatus.
In order to achieve the above object, the present invention has the following constitutions.
In a first aspect of the invention, there is provided a heating apparatus for bump bonding, comprising:
a wafer turning member, on which a semiconductor wafer is placed for bump bonding, for rotating the placed semiconductor wafer on the wafer turning member in a circumferential direction of the wafer;
a turning unit for rotating the wafer turning member along the circumferential direction; and
a wafer heating unit, on which the wafer turning member is placed, for heating the semiconductor wafer to a bump bonding temperature via the wafer turning member, the wafer heating unit being disposed in spite of the rotation of the wafer turning member.
In the first aspect of the invention, the heating apparatus for bump bonding may further comprise a control unit for controlling operation of the turning unit so that the wafer turning member is rotated at a turning angle required for the semiconductor wafer placed on the wafer turning member.
In the heating apparatus for bump bonding, the wafer turning member may have a wafer stage on which the semiconductor wafer is placed, and a turntable on which the wafer stage is placed and for holding the wafer stage by suction operation, the turntable being placed on the wafer heating unit.
In the heating apparatus for bump bonding, the wafer heating unit may have a turntable mounting plate on which the turntable is placed; a heater inserted and extended along a hole, the hole being formed in the turntable mounting plate along a direction perpendicular to a thicknesswise direction of the turntable mounting plate; and a support member for supporting the turntable mounting plate, the support members extending along a direction perpendicular to both directions of the thicknesswise direction and the extending direction of the heater.
In the heating apparatus for bump bonding, the turntable may have teeth formed at a peripheral part of the turntable, and
the turning unit comprises a driving source, a gear wheel engaged with the teeth of the turntable, and a rotational-force transmission mechanism for preventing heat of the turntable from transferring to the driving source and for transmitting a driving force generated by the driving source to the gear wheel to thereby turn the gear wheel.
The heating apparatus for bump bonding may further comprise a lifter unit for lifting and lowering the wafer turning member between a heating position and a transfer position along a thicknesswise direction of the semiconductor wafer placed on the wafer turning member,
the heating position being a position where the wafer turning member makes contact with the wafer heating unit so that the semiconductor wafer is heated to the bump bonding temperature via the wafer turning member, and the transfer position being a position where the wafer turning member is positioned when the wafer turning member is turned.
The heating apparatus for bump bonding may further comprise a blow unit for floating the semiconductor wafer placed on the wafer turning member from the wafer turning member by gas blow, and a regulating unit for performing positional regulation of the semiconductor wafer on the wafer turning member while the semiconductor wafer is floating from the wafer turning member.
In the heating apparatus for bump bonding, the semiconductor wafer is a wafer on which SAW filter devices are formed, and when the SAW filter devices are formed along a skewed direction which is skewed to a crystal orientation of the wafer prior to formation of the SAW filter devices, the turning angle required for the semiconductor wafer placed on the wafer turning member by operation control of the turning unit is an angle which depends on a difference between the crystal orientation and the skewed direction.
In a second aspect of the invention, there is provided a bump bonding method comprising:
mounting a semiconductor wafer, on which bumps are to be formed, onto a wafer turning member;
turning only the wafer turning member with the semiconductor wafer placed thereon along a circumferential direction of the semiconductor wafer at a turning angle required for the semiconductor wafer without turning a wafer heating unit provided for heating the semiconductor wafer to a bump bonding temperature via the wafer turning member; and
after the turning, bonding the bumps on the semiconductor wafer at the bump bonding temperature.
In a third aspect of the invention, there is provided a bump forming apparatus which comprises the heating apparatus for bump bonding of the first aspect.
In a fourth aspect of the invention, there is provided a semiconductor wafer on which a bump is formed by the bump bonding method of the second aspect.
In a fifth aspect of the invention, there is provided a semiconductor wafer on which bumps are formed in a circuit by a process comprising, after forming the circuit along a direction which is different from a crystal orientation of the semiconductor wafer and is skewed with respect to the crystal orientation, turning the semiconductor wafer at an angle which depends on a difference between the crystal orientation and the skewed direction.
As described in detail above, according to the heating apparatus for bump bonding in the first aspect of the present invention, as well as to the bump bonding method in the second aspect, the apparatus has a turning member, a turning unit and a wafer heating unit, wherein the turning member is turned by the turning unit without turning the wafer heating unit so that the semiconductor wafer mounted on the turning member is turned. Therefore, since the wafer heating unit is not turned, an apparatus configuration can be made compact. Besides, since the turning member is turned directly by the turning unit, a turning angle of the semiconductor wafer can be implemented with higher accuracy as compared with a conventional gas floating type.
Also, in the bump forming apparatus equipped with the aforementioned heating apparatus for bump bonding in the third aspect of the invention, the turning angle of the semiconductor wafer can be controlled with high accuracy as described above. Therefore, bump forming positions on the semiconductor wafer can be controlled with higher accuracy as compared with the conventional apparatus.
In the semiconductor wafer of the fourth aspect of the invention, on which bumps are bonded with the aforementioned bump bonding method of the second aspect, the turning angle of the semiconductor wafer can be controlled with high accuracy as described above. Therefore, bumps can be formed at bump forming positions on the semiconductor wafer with higher accuracy as compared with the conventional counterpart.